In conventional bank note processing apparatus the bank notes are generally singled from a stack and led past a sensor device by means of a transport path. The individual bank notes are checked by sensors of the sensor device and dependent on the checking result are supplied to certain final destinations or stacker units. Accordingly, several stacker units can be available, which stack the bank notes of the different categories into units of an adjustable piece number. If for example bank notes of a certain category are to be stacked in units of a piece number of 100 bank notes, it is necessary to perform a separation in the continuous flow of bank notes between the one hundredth bank note and the following bank note meant for the same stacker after the one hundredth bank note has arrived at the stacker.
In this context EP 0 119 814 B1 describes a spiral slot stacker for paper sheets, wherein the singled paper sheets are fed via a supply unit into slots of a stacker wheel, with a stack deposit, in which the paper sheets, which are stripped off from the stacker wheel by means of a fixed stripper, are stacked. Furthermore the spiral slot stacker comprises swiveling separators on which, when in an accommodation position in which they are fixed above the stack deposit, paper sheets which are stripped off from the stacker wheel are stacked intermediately. When the separators are subsequently swiveled out of the accommodation position, the intermediately stacked bank notes collide with the fixed stripper, are stripped off and stacked on the stack deposit. The use of the separators enables the separation of the paper sheets supplied to the spiral slot stacker into units of a predetermined piece number by removing paper sheets which are stacked on the stack deposit and intermediately stacking the subsequent paper sheets on the separators. However, at high transport speeds the secure function of the spiral slot stacker cannot be guaranteed, since relatively great actuating forces have to be applied in order to accelerate the separators.
Instead of the use of separators the published patent application DE 102 34 970 A1 suggests to intermediately stack bank notes in the stacker wheel of a spiral slot stacker. If for example the bank notes supplied to the spiral slot stacker are to be separated into units of 100 bank notes each on a stack deposit, after the one hundredth bank note was stripped off from the stacker wheel the bank notes can be intermediately stacked in the slots of the stacker wheel for such a time until the stack deposit has been emptied. Therein, a stripper for stripping the bank notes comprises two movable components, i.e. a first part which is moved out of the strip-off position during the intermediate stacking procedure, and a second part which is rotated along with the rotating stacker wheel during the intermediate stacking procedure.
In a first embodiment, the second part of the stripper rotates along with the stacker wheel for such a time until the stack deposit is prepared to accommodate a next bank-note stack and the second part of the stripper again has reached its strip-off position in which it is then fixed. The bank notes accommodated in the stacker wheel are thus stripped off and stacked on the stack deposit. Then the first part of the stripper can be moved back to its strip-off position, too. This embodiment bears the risk of the collision of the bank note and the second part of the stripper, which temporarily rotates along with the stacker wheel, during the insertion of the bank note into the stacker wheel.
In a second embodiment, like in the first embodiment, the first part of the stripper is moved out of the strip-off position and the second part is moved along with the stacker wheel while the stack deposit is emptied. However, the second, rotating-along part of the stripper is subsequently brought back to its strip-off position against the rotation direction of the stacker wheel and is fixed in order to strip the bank notes off from the stacker wheel. In this case the stack deposit has to be prepared very quickly for the accommodation of the next stack of bank notes to be stacked, since the second part of the stripper otherwise moves too far away from the stack deposit and the bank notes would no longer be reliably stacked on the stack deposit during the return of the stripper. In order to avoid this problem, in the published patent application DE 102 34 970 A1 therefore again the use of an auxiliary stack deposit or separator is suggested in order to intermediately stack the bank notes stripped off from the stacker wheel while the proper stack deposit is emptied.